Journal of Physical Chemistry, Vol.98, No.36, 9002-9008, 1994
Molecular-Conformation and Magnetic-Behavior of Macrocyclic Columnar Liquid-Crystals
We report the results of deuterium NMR experiments performed on macrocyclic columnar mesogens. The columnar hexagonal mesophase, aligned in a static magnetic field, exhibits an unusual positive anisotropy of the diamagnetic tenser so that the column axes tend to orient themselves parallel to the direction of the applied field. A different kind of alignment can be detected when, by rotating the sample, the average columnar axes direction is made perpendicular to the field : the molecular cores tend to orient their long axis perpendicular to the field direction. This is the first case, to our knowledge, where a field-induced transversal alignment is observed in columnar mesophases. This peculiar alignment allowed the assignment of the flattened cone conformation to the macrocyclic core in the mesophase.